From: John Fastabend <john.fastabend@gmail.com>
To: tong@infragraf.org, bpf@vger.kernel.org, quentin@isovalent.com,
daniel@iogearbox.net
Cc: Tonghao Zhang <tong@infragraf.org>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>
Subject: RE: [bpf-next v3] bpftool: profile online CPUs instead of possible
Date: Thu, 02 Feb 2023 17:46:25 -0800 [thread overview]
Message-ID: <63dc6771a8400_688f120896@john.notmuch> (raw)
In-Reply-To: <20230202131701.29519-1-tong@infragraf.org>
tong@ wrote:
> From: Tonghao Zhang <tong@infragraf.org>
>
> The number of online cpu may be not equal to possible cpu.
> "bpftool prog profile" can not create pmu event on possible
> but on online cpu.
>
> $ dmidecode -s system-product-name
> PowerEdge R620
> $ cat /sys/devices/system/cpu/possible
> 0-47
> $ cat /sys/devices/system/cpu/online
> 0-31
>
> Disable cpu dynamically:
> $ echo 0 > /sys/devices/system/cpu/cpuX/online
>
> If one cpu is offline, perf_event_open will return ENODEV.
> To fix this issue:
> * check value returned and skip offline cpu.
> * close pmu_fd immediately on error path, avoid fd leaking.
>
> Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command")
> Signed-off-by: Tonghao Zhang <tong@infragraf.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
next prev parent reply other threads:[~2023-02-03 1:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 13:17 [bpf-next v3] bpftool: profile online CPUs instead of possible tong
2023-02-03 1:46 ` John Fastabend [this message]
2023-02-03 7:10 ` patchwork-bot+netdevbpf
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